The present invention relates to mass spectrometers and, more particularly, to a mass spectrometer suitable for reduction of its size and weight.
In a mass spectrometer, an ionized measurement sample is analyzed for its mass in a mass spectroscopy section. While the mass spectroscopy section is housed in a vacuum chamber and maintained at a high vacuum of 0.1 Pa or lower, ionization of a measurement sample is performed in the atmospheric pressure as shown in U.S. Pat. No. 7,064,320 or in a reduced pressure of about 10 to 100 Pa as shown in U.S. Pat. No. 4,849,628, so that there is a difference between a pressure in an environment for execution of ionization and a pressure in an environment for execution of mass spectroscopy. Accordingly, in order to introduce an ionized measurement sample to the mass spectroscopy section while keeping the degree of vacuum (pressure) in the mass spectroscopy section within a range capable of mass spectroscopy, a differential pumping scheme has been proposed as shown in U.S. Pat. No. 7,592,589. Further, WO 2009/023361 proposes, in addition to the differential pumping scheme, a scheme in which an ionized measurement sample is introduced intermittently to the mass spectroscopy section. Furthermore, in order to improve measurement sensitivity of mass spectroscopy, ionization schemes utilizing dielectric barrier discharge phenomena have been proposed as ionization schemes capable of highly efficient ionization in WO 2009/102766 and WO 2009/157312.